The Shallow Survey was undertaken mostly in the first year of operations and continues during full moon periods. Each visit measures objects from 9 to 17 mag in all six bands. It provides the overall calibration of the Southern Sky Survey and allows the survey to be tied to the Hipparcos and Tycho catalogs (and other photometric systems established in the southern hemisphere, such as APASS). The Main Survey will be calibrated from Shallow Survey observations of spectrophotometric standards.

Most of SkyMapper's observing time is now dedicated to the Main Survey. This has an expected depth (in AB mags) for a signal-to-noise ratio of 5 in 2.5" seeing, of:

u

v

g

r

i

z

Single epoch

19.5

19.5

21.0

21.0

20.0

19.0

Saturation

10.0

10.5

13.0

13.0

11.0

10.5

Exp. time (s)

100

100

100

100

100

100

Final depth

20.5

20.5

21.7

21.7

20.7

19.7

The survey scheduler aims to finish a field mostly within one moon period. A first visit in dark conditions establishes a colour sequence with all six bands observed in the space of 20 minutes. Further visits in subsequent nights under dark or grey sky conditions add exposure pairs in g- and r-band, while in grey or bright conditions pairs in i- and z-band are added. A second colour sequence in dark conditions finishes the set. Further pairs in i- and z-band are also observed during astronomical twilight. These twilight observations may be separated by many months from the night-time visits.